Process for manufacturing a composite wooden board



F. FAHRNI Aug. 10, 1954 I PROCESS FOR MANUFACTURING A COMPOSITE WOODENBOARD Filed Nov. 24, 1945 3&1

* INVENTOR. Em e/{ .BY 77041.4

Patented Aug. 10, 1954 OFFICE 2,686,143 PROCESS FOR MANUFACTURING A COM-POSITE WOOD EN BOARD Fred Fahrni, Zurich, Switzerland ApplicationNovember 24, 1945,

Serial No. 630,619

In Germany April 25, 1942 Section 1, Public Law Patent expires 11Claims.

The object of the present invention is a process for the manufacturingof fabricated sheets or compound compressed plates made of layers ofpieces of wood and binding materials.

The products so far known of this type, made of wood pieces and the likemixed with a binding substance, showed great disadvantages.

When the pieces of wood were of coarser splinter shaped material, thesurface is too rough and unsuitable for many uses, as for instance forflooring, cabinet-makers work and so on.

Where a finer material is used, which necessitated a larger amount ofbinding substances, such plates are too expensive, all the more whencoarser pieces of wood are used and reduced to a finer material, whichnecessitates a larger use of energy.

In addition compressed masses of fine material alone with water contentof 8% and over, when compressed hot, presented difficulties, because thesteam could not escape and steam bubbles spoiled the production.

This disadvantage can be obviated by placing a metal sieve or the likebetween the heated press and the mass to be compressed, which however onthe other hand makes it impossible to produce plates smooth on bothsides, since a sieve mark on one of the sides prevents it.

These difficulties have now been overcome by the process according tothe present invention by superimposing at first a basic layer of fine,selected material, then a middle layer of coarser material, needing lessbinding substance, and finally a covering layer of fine, selectedmaterial the mass so obtained being then compressed in one operation.

A major advantage of this process is that due to the presence of thesaid middle layer, relatively coarse Wood waste of any shape, colour andsize without any great additional use of materials for binding may beused for making compound compressed good looking wood plates.

The plate has, nevertheless, as a result of the special basic andcovering layers, a perfectly fine and equal surface, so that its usesare almost endless.

The porous structure of the coarser inner layer serves simultaneously asa channel for steam so that on both sides smooth plates are obtained.

More beautiful and smoother surfaces are obtained by keeping the outerlayers damper than the inner ones during the compression, so that thegeneral development of steam is relatively slight. Thus warping of theplates will be avoided.

It is further advantageous to add larger quan- 690, August 8, 1946 April25, 1962 titles of binding material and of substances ensuring a betterappearance and resistance to outside influences to the pieces of wooddestined for the outer layers. Such substances consist for instance ofwaterproofing or additions to achieve a greater resistance to humidity,to harden the pieces of wood, to add colours to the same or forheightening of the powers of resistance against mildew and mold and soon. Thereby, in spite of a great reduction of production costs, thewhole surface of the outer surface is particularly good and firm.

The accompanying drawing shows a sectional view of what a fabricatedsheet or plate, made according to the present invention, may look like,and illustrates a partial and half schematical embodiment of a device,given by way of example, for the manufacture of wood plates according tothe present process.

Fig. 1 is the said sectional view.

Fig. 2 shows how the three layers may be filled into frames.

Fig. 3 is a detailed view of the filling apparatus for the finermaterial, forming the basic and covering layers.

Fig. 4 is a detail of the of the coarser material.

In the plate shown in cross section in Fig. 1 the two outer layers, offiner material, I, 2 with mirror smooth upper surface 3 or i, areimmeiately recognizable, as also the middle layer 5 of coarser material.

The size of such a plate is, of course, limited only by the possibilityof compressing bigger upper surfaces.

The three layers can, by means of a very Simple apparatus according toFig. 2, be superimposed.

On a bed or guide 6 frames can be moved or conveyed to and fro orlengthwise.

Such a frame is shown in i.

It first performs a to and fro movement according to the arrows 8between the extreme positions 1 and la, and this under a filling funnel,which serves to lay the fine basic layer.

Figure 3, further described below, gives more details of such a funnel.

The Whole layout must of course so be conceived that an equallydistributed layer results.

This first operation terminated, the frame is pushed to R where it, bymeans of the arrows Iii, is moved to and fro between the positions Itand 70. A channel H, which can be constructed, for example, as a shakingchannel serves to feed the middle layer, made of coarser maapparatus forthe filling terial, on to the basic layer already in the frame.

After termination of this second operation the frame is pushed furthertowards 5d, where it again, according to to the arrows l2, carries out ato and fro movement.

A funnel it serves, thereby, like the funnel 9, to lay the uppercovering layer of fine material.

Finally the triple layered mass will be subjected to the compressingoperation.

Now will be shown shortly according to Fig. 3, how the filling of thebasic or covering layer may be carried out.

The frame l is here shown in the shape of a form closed at the lowerside in reality, however, it is executed as a movable frame of which thelower side consists of a sheet of polished metal.

Its to and fro movement, according to arrows 8, arises with the help ofan endless chain l5 propelled. over two rollers like 14, with a pin ll,reaching into the lower fork H; of the frame.

If the roller li turns in the direction of the arrow, it is easy to seethat the pin, lying on the upper part of the chain, first propels theframe to the left.

If it, however, arrives over the roller, it will slide downwards in thefork i6 and the desired turning of the carrying direction is obtained.This operation will take place in the same manner to the right, outsidethe drawing, in crossing the roller, not shown, opposite roller i l, butin the opposing direction.

In the upper part of the funnel 9 there is a slider it, on which can belaid the finer material it, which is first prepared and in some cases,weighed.

Under this slider rotates a spur-cylinder so in the direction of thearrow 2 i. It breaks up possible lumps in the material that it feeds outof the slider 58 to a number of cylinders 22 closely continguous to eachother and square in profile,

which distribute this material evenly over the shaking sieve 23.

The sieve, thrust to and fro by the lever 24, can accomplish about 80complete movements to the minute, and the cylinders 22, driven overstrap 25, about the same number of rotations to the minute, while thespur cylinder 20, for example, turns ten to twelve times slower.

The evenly distributed fine material falls into the frame 1 through thelower part of funnel 2%.

The channel l l, the upper part of which is visible in Fig. l, forcoarser material, can be fed for example with the help of a bucket-chain2'! raising the material in question out of a pit.

Finally, the second funnel i3 would be constructed something like thefirst, that is to say according to the execution according to Fig. 3.

Of course the briefly described contrivances can be completed by furtherapparatus, as for example automatic weighing devices and the wholeprocess could be run partly by hand, partly or completely automatically.

It should now be added that it is expedient that, when the outer layersare of a markedly finer material than the inner, these latter should becompressed before the finer layers are filled. By the pre-compressing ofthe coarser inner layers the projection of parts into the outer surfacewill be avoided and further the space between the single coarser pieceswill be reduced, so that complete covering may be carried out with aminimum of covering material.

The mixture, composed of pieces of wood and binding substances, placedin the frame, can next, be compressed in the said frame and then withoutframe submitted to the main compression. This has the advantage that thepress serving for the main compression, which is usually a hot press,need not be constrained, either in its measurements or its execution tolimits defined by the shape of the frames, whereby its uses areconsiderably increased.

Following are some examples of execution of the process according to thepresent invention:

Example 1.-Waste from veneering, ends, and furniture factories are soworked in a splitting machine that pieces result between 5 and 50 mm.long, about 5 to 10 mm. wide and from one to several millimeters thick.Other shorter and thicker little pieces occurring do not matter. Thismaterial is, possibly previously waterproofed with 2.5% paraffine, driedto a humidity content of 5% and with a 3.5% of a binding substance, forinstance a condensate of urea-formaldehyde obtained in powder formaccording to an already known process with the suitable catalyst, whichrapidly dissolves the binding substance in question in the heat and thenmixed with water.

For the covering layers the material is dustfree, clean white soft wood,planing shavings or other thin and flat kinds of shavings, which aremixed with 14% of binding substances and finally kept to a humiditycontent of 1 3% by sprinkling with water.

In a mobile form having a sheet-metal base like l of Figs. 2 and 3, somany thin layers are formed through the to and fro movement, that theseare, when finally compressed, 2 mm. thick. On this basic layer are againspread so many single layers of as much previously selected coarsermaterial as to produce when compressed, a thickness of 21 mm.

These two layers can in some cases be precompressed and thereover singlelayers of glued flat shavings of the same mixture will be filled in upto 2 mm., in order to produce the covering layer.

The whole mixture will now be rapidly precompressed, so that it becomessufficiently coherent and provided with a covering sheet of metal, becompressed without frame in, for instance, a press heated to 120 C. with10 kg. pressure per square cm.

The product obtained is a beautiful, firm and on both sides very smoothplate with a pale, veneer-like surface, which is very suitable forfurniture or cabinet-making, for doors as for walls and ceilingcoverings. The covering layers may also be stained. and polished andthus substituted for expensive veneering.

Example 2.Uneven waste, such as sawmill waste, splinters, trunk disks,etc., are broken into coarser, splinter shaped parts and dried to about4%. 800 parts by weight of this material are mixed, according to thealready known process, with 32 parts by weight of a binding substance,fed uniformly into a form as described under (1) and pro-compressed;this accounts to about 4% of binder.

Uneven waste of hard wood is split on a suitable machine into thin,fiat, planing shavings shaped pieces of wood, which are then furtherreduced to scale shaped bits. After drying out to 10% humidity content150 parts by weight as well as 50 parts by weight finer hard wood sawshavings are mixed with 20 parts by weight of a waterproof bindingsubstance and 20 parts by weight of water. 10 parts by weight of hardwax powder are then added. The mass thus mixed layers of the sheet intoone body.

What I claim is:

l. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; applying 3.5%of a binder substance to said coarse wood pieces so as to obtainslightly humid binder treated coarse wood pieces; cutting other woodmaterial to substantially flat shavings; applying 14% of a bindersubstance to said fiat wood shavings so as to obtain humid bindertreated fiat wood shavings; forming a first humid surface layer of saidhumid binder treated fiat wood shavings; superimposing on said firstsurface layer a slightly humid porous core layer of said slight- 1yhumid binder treated coarse Wood pieces; superimposing upon said porouscore layer a second humid surface layer of said humid binder treatedfiat wood shavings; and applying a pressure of substantially 1O kilogramper square cm. at a temperature of substantially 120 C. to saidsuperimposed layers so as to cause a firm adhesion of said bindertreated fiat wood shavings in said surface layers and of said bindertreated coarse wood pieces in said porous core layer to one another andto cause also a firm adhesion of the layers themselves to one another,while permitting the steam formed by applying heat to escape into saidporous core layer of coarse wood pieces, thereby obtaining a compositewooden board composed of a porous core layer and two substantiallywater-impervious surface layers firmly adhering to said porous corelayer and having a high tensile strength.

2. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; ap plying 4%of a binder substance to said coarse wood pieces so as to obtainslightly humid binder treated coarse wood pieces; cutting other woodmaterial to substantially fiat shavings; applying of a binder substanceto said flat wood shavings so as to obtain humid binder treated fiatWood shavings; forming a first humid surface layer of said humid bindertreated fiat wood shavings; superimposing on said first surface layer aslightly humid core layer of said slightly humid binder treated coarsewood pieces, said core layer having a porous structure forming airchannels; superimposing upon said porous core layer a second humidsurface layer of said humid binder treated flat wood shavings; andapplying a pressure of substantially 25 kilogram per square cm. at atemperature of substantially 150 C. to said superimposed layers so as tocause a firm adhesion of said binder treated fiat wood shavings in saidsurface layers and of said binder treated coarse wood pieces in saidporous core layer to one another and to cause also a firm adhesion ofthe layers themselves to one another, while permitting the steam formedby applying heat to escape into said air chamiels in said porous corefiat wood shavings; superimposing .6 layer, thereby obtaining acomposite wooden board composed of a porous core layer and twosubstantially water-impervious surface layers firmly adhering to saidporous core layer and having a high tensile strength.

3. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; drying saidcoarse wood pieces to a humidity of approximately 5%; applying 3.5% of abinder substance to said coarse wood pieces so as to obtain bindertreated coarse wood pieces; cutting other wood material to substantiallyfiat shavings; applying 14% of a binder substance to said fiat woodshavings so as to obtain binder treated flat wood shavings; keeping saidfiat wood shavings at a humidity of approximately 18%; forming a corelayer of said binder treated coarse wood pieces; forming a surface layerof said binder treated fiat wood shavings; superimposing said core layerand said surface layer upon each other; and applying pressure to saidsuperimposed layers so as to cause firm adhesion of said binder treatedcoarse wood pieces and said binder treated flat wood shavings to oneanother, thereby obtaining a composite wooden board composed of a porouscore layer and a surface layer being substantially impervious to waterand having a high tensile strength and firmly adhering to said porouscore layer.

4. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; drying saidcoarse wood pieces to a humidity of approximately 5%; applying 3.5% of abinder substance to said coarse Wood pieces so as to obtain bindertreated coarse wood pieces; cutting other wood material to substantiallyfiat shavings; applying 14% of a binder substance to said flat woodshavings so as to obtain binder treated fiat wood shavings; keeping saidfiat wood shavings at a humidity of approximately 18%; forming a corelayer of said binder treated coarse wood pieces; forming a surface layerof said binder treated said core layer and said surface layer upon eachother; and applying a pressure of substantially 10 kilogram per squarecm. at a temperature of substantially C. to said superimposed layers soas to cause firm adhesion of said binder treated coarse wood pieces andsaid binder treated flat wood shavings to one another, thereby obtaininga composite wooden board composed of a porous core layer and a surfacelayer being substantially impervious to water and having a high tensilestrength and firmly adhering to said porous core layer.

5. A process of manufacturing a composite Wooden board, comprising thesteps of making coarse wood pieces from a wooden material said woodpieces having substantially a length between 5 and 50 mm., a widthbetween 5 and 10 mm., and a thickness of at least 1 mm. drying saidcoarse wood pieces to a humidity of approximately 5% applying 3.5% of abinder substance to said coarse wood pieces so as to obtain bindertreated coarse Wood pieces; cutting other wood material to substantiallyfiat shavings; applying 14% of a binder substance to said fiat woodshavings so as to obtain binder treated fiat wood shavings; keeping saidfiat wood shavings at a humidity of approximately 18%; forming a corelayer of said binder treated coarse wood pieces; forming a surface layerof said binder treated fiat wood shavings ;-superimposing-said corelayer and said surface layer upon each other; and applying a pressure ofsubstantially 10 kilogram per square cm. at a temperature ofsubstantially 120 C. to said superimposed layers so as to cause firmadhesion of said binder treated coarse wood pieces and said bindertreated fiat wood shavings to one another, thereby obtaining a compositewooden board composed of a porous core layer and a surface layer beingsubstantially impervicue to water and having a high tensile strength andfirmly adhering to said porous core layer.

6. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; drying saidcoarse wood pieces to a humidity of ap proximately 4%; applying arelatively small quantity of a binder substance to said coarse woodieces; cutting other wood material to substantially fiat shavings;applying a relatively large quantity of a binder substance to said flatwood shavings so as to obtain binder treated flat wood shavings; keepingsaid flat wood shavings at a humidity of approximately 18%; forming acore layer of said binder treated coarse wood pieces;

forming a surface layer of said binder treated flat wood shavings;superimposing said core layer and said surface layer upon each other;and applying pressure to said superimposed layers so as to cause firmadhesion of said binder treated coarse wood pieces and said bindertreated fiat wood shavings to one another, thereby obtaining a compositewooden board composed of a porous core layer and a surface layer beingsubstantially impervious to water and having a high tensile strength andfirmly adhering to said porous core layer.

7. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; drying saidcoarse wood pieces to a humidity of approximately i%; applying 4% of abinder substance to said coarse wood pieces; cutting other wood materialto substantially flat shavings; applying 10% of a binder substance tosaid fiat wood shavings so as to obtain binder treated fiat woodshavings; keeping said flat wood shavings at a humidity of approximately18%; forming a core layer of said binder treated coarse wood pieces;forming a surface layer of said binder treated flat wood shavings;superimposing core layer and said surface layer upon each other; andapplying pressure to said superimposed layers so as to cause firmadhesion of said binder treated coarse wood pieces and said bindertreated fiat wood shavings to one another, thereby obtaining a compositewooden board composed of a porous core layer and a surface layer beingsubstantially impervious to water and having a high tensile strength andfirmly adhering to said porous core layer.

3. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material said woodpieces having substantially a length between 5 and 50 mm, a widthbetween 5 and and a thickness or at least 1 mm.; drying said coarse woodpieces to a humidity of approximately 4%; applying a relatively smallquantity of a binder substance to said coarse wood pieces, cutting otherwood material to substantially flat shavings; applying a relativelylarge quantity of a binder substance to said flat wood shavings so as toobtain binder treated fiat wood shavings; keeping said flat woodshavings at a humidity of approximately 18%; forming a core layer ofsaid said binder treated coarse wood pieces; forming a surface layer ofsaid binder treated fiat wood shavings; superimposing said core layerand said surface layer upon each other; and applying pressure to saidsuperimposed layers so as to cause firm adhesion of said binder treatedcoarse wood pieces and said binder treated fiat wood shavings to oneanother, thereby obtaining a composite wooden board composed of a porouscore layer and a surface layer being substantially impervious to waterand having a high tensile strength and firmly adhering to said porouscore layer.

9. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material said woodpieces having substantially a length between 5 and 50 min, a widthbetween 5 and 10 mm, and a thickness of at least 1 mm.; drying saidcoarse wood pieces to a humidity of approximately 4%; applying 4% of abinder substance to said coarse wood pieces; cutting other wood materialto substantially flat shavings; applying 10% of a binder substance tosaid flat wood shavings so as to obtain binder treated flat woodshavings; keeping said flat wood shavings at a humidity of approximately18%; forming a core layer of said binder treated coarse wood pieces;forming a core layer of said binder treated coarse wood pieces; forminga surface layer of said binder treated fiat wood shavings; superimposingsaid core layer and said surface layer upon each other; and applyingpressure to said superimposed layers so as to cause firm adhesion ofsaid binder treated coarse wood pieces and said binder treated flat woodshavings to one another, thereby obtaining a composite wooden boardcomposed of a porous core layer and a surface layer being substantiallyimpervious to water and having a high tensile strength and firmlyadhering to said porous core layer.

10. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material; drying saidcoarse wood pieces to a humidity of approximately 4%; applying 4% of abinder substance to said coarse wood pieces; cutting other wood materialto substantially flat shavings; applying 10 of a binder substance tosaid flat wood shavings so as to obtain binder treated flat woodshavings; keeping said fiat wood shavings at a humidity of approximately18%; forming a core layer of said binder treated coarse wood pieces;forming a surface layer of said binder treated fiat wood shavings;superimposing said core layer and said surface layer upon each other;and applying a pressure of substantially 25 kilogram per square cm. at atemperature of substantially C. to said superimposed layers so as tocause firm adhesion of said binder treated coarse wood pieces and saidbinder treated flat wood shavings to one another, thereby obtaining acomposite wooden board composed of a porous core layer and a surfacelayer being substantially impervious to water and having a high tensilestrength and firmly adhering to said porous core layer.

11. A process of manufacturing a composite wooden board, comprising thesteps of making coarse wood pieces from a wooden material said woodpieces having substantially a length between 5 and 50 mm., a widthbetween 5 and 10 mm, and a thickness of at least 1 mm.; drying saidcoarse wood pieces to a humidity of approximately 4% applying 4% of abinder substance to said coarse wood pieces; cutting other wood materialto substantially flat shavings; applying 10% of a binder substance tosaid flat wood shavings so as to obtain binder treated fiat woodshavings; keeping said fiat wood shavings at a humidity of approximately18%; forming a core layer of said binder treated coarse wood pieces;forming a surface layer of said binder treated fiat wood shavings;superimposing said core layer and said surface layer upon each other;and applying a pressure of substantially 25 kilogram per square cm. at atemperature of substantially 150 C. to said superimposed layers so as tocause firm adhesion of said binder treated coarse wood pieces and saidbinder treated flat wood shavings to one another, thereby obtaining acomposite wooden board composed of a porous core layer and a surfacelayer being substantially impervious to water and having a high tensilestrength and firmly adhering to said porous core layer.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,033,411 Carson Mar. 10, 1 36 2,066,734 Loetscher Jan. 5,1937 2,067,012 Loetscher Jan. 5, 1937 2,078,269 Nevin Apr. 27, 19372,080,078 Mason May 11, 1937 2,120,137 Mason June 7, 1938 2,124,921Lederer July 26, 1938 2,347,697 Levey May 2, 1944

1. A PROCESS OF MANUFACTURING A COMPOSITE WOODEN BOARD, COMPRISING THESTEPS OF MAKING COARSE WOOD PIECES FROM A WOODEN MATERIAL; APPLYING 3.5%OF A BINDER SUBSTANCE TO SAID COARSE WOOD PIECES SO AS TO OBTAINSLIGHTLY HUMID BINDER TREATED COARSE WOOD PIECES; CUTTING OTHER WOODMATERIAL TO SUBSTANTIALLY FLAT SHAVINGS; APPLYING 14% OF A BINDERSUBSTANCE TO SAID FLAT WOOD SHAVINGS SO AS TO OBTAIN HUMID BINDERTREATED FLAT WOOD SHAVINGS; FORMING A FIRST HUMID SURFACE LAYER OF SAIDHUMID BINDER TREATED FLAT WOOD SHAVINGS; SUPERIMPOSING ON SAID FIRSTSURFACE LAYER A SLIGHTLY HUMID POROUS CORE LAYER OF SAID SLIGHTLY HUMIDBINDER TREATED COARSE WOOD PIECES; SUPERIMPOSING UPON SAID POROUS CORELAYER A SECOND HUMID SURFACE LAYER OF SAID HUMID BINDER TREATED FLATWOOD SHAVINGS; AND APPLYING A PRESSURE OF SUBSTANTIALLY 10 KILOGRAM PERSQUARE CM. AT A TEMPERATURE OF SUBSTANTIALLY 120* C. TO SAIDSUPERIMPOSED LAYERS SO AS TO CAUSE A FIRM ADHESION OF SAID BINDERTREATED FLAT WOOD SHAVINGS IN SAID SURFACE LAYERS AND OF SAID BINDERTREATED COARSE WOOD PIECES IN SAID POROUS CORE LAYER TO ONE ANOTHER ANDTO CAUSE ALSO A FIRM ADHESION OF THE LAYERS THEMSELVES TO ONE ANOTHER,WHILE PERMITTING THE STEAM FORMED BY APPLYING HEAT TO ESCAPE INTO SAIDPOROUS CORE LAYER OF COARSE WOOD PIECES, THEREBY OBTAINING A COMPOSITEWOODEN BOARD COMPOSED OF A POROUS CORE LAYER AND TWO SUBSTANTIALLYWATER-IMPERVIOUS SURFACE LAYERS FIRMLY ADHERING TO SAID POROUS CORELAYER AND HAVING A HIGH TENSILE STRENGTH.